It is widely held that free speech is a distinctive and privileged social kind. But what is free speech? In particular, is there any unified phenomenon that is both free speech and which is worthy of the special value traditionally attached to free speech? We argue that a descendent of the classic Millian justification of free speech is in fact a justification of a more general social condition; and, via an argument that 'free speech' names whatever natural social kind is justified by the best arguments, that free speech is therefore this more general condition. This condition involves not merely the orthodox freedom (in some sense) of speakers to distribute words, but also two less frequently acknowledged dimensions of free speech: audience understanding and consideration. We conclude with some discussion of the policy implications of this conception of free speech.